DE102012209172A1 - Lens with internal reflecting reflection layer - Google Patents

Abstract

The lens (12) has a transparent main body (13), wherein a surface (14, 15) of the main body is at least partially covered with an internally reflecting reflection layer (17), the lens at least a first focal point (F1) and at least one second focal point (F2), at least the first focal point lies at least partially on an unoccupied surface area of the base body (15) and at least one phosphor element (18) rests against the base body at a contact area (19) which has at least one first focal point. A lighting device (11) has at least one lens and at least one light source (21) for irradiating primary light (P) on at least one first focal point through the main body of the lens, wherein the arranged at this at least one first focal point arranged at least one phosphor element is to convert the primary light at least partially into secondary light (S) of a different wavelength. The lens is particularly useful in a vehicle headlamp, projection device, industrial image processing or medical lighting and diagnostic applications.

Description

The invention relates to a lens having a transparent base body, wherein a surface of the base body is at least partially covered with an internally reflecting reflection layer and the lens has at least one first focal point and at least one second focal point. The invention is particularly applicable to vehicle lighting, particularly with a headlamp, as well as to image projection (eg, for a video projector, etc.), industrial image processing, and medical lighting and diagnostic applications.

WO 2011/127286 A1 discloses illumination devices that use primary or excitation light and a wavelength-converting phosphor for illumination, the phosphor being excited by multiple excitation light sources from both sides to achieve increased brightness. The excitation light incident on the two sides can have the same color or different colors. Light-separating structures are provided on both sides of the phosphor to separate the excitation light and the wavelength-converted (secondary) light through the phosphor. In one embodiment, a second light-separating structure may be in the form of an ellipsoidal hollow reflector with a small window. The phosphor is disposed at or near a focal point of the hollow reflector, and a light-collecting element is disposed at or near another focal point of the hollow reflector. The excitation light is irradiated through the window onto the phosphor. The converted light is reflected by the hollow reflector on the light-collecting element.

US 2007/019408 A1 discloses a lighting device with a phosphor coated color wheel for producing colored light. In one embodiment, the illumination device has a reflector, a light source and a light-collecting element in addition to the color wheel. The reflector may be used as an optically transmissive element, e.g. B. made of glass or plastic, be formed with a first and a second curved surface. The first surface may have a recess for receiving the light source, while the second, z. Ellipsoidal, surface is a reflective surface which is reflective of the (primary) light of the light source but transparent to the (secondary) light converted by the phosphor of the color wheel. For this purpose, light radiated by the light source through the reflector is reflected onto the color wheel rotating at a distance below the optically translucent element.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a lens having a transparent body ("base body"), wherein a surface of the base body is at least partially covered with an internally reflecting reflection layer. In particular, a layer which has at least one surface reflecting in the direction of the main body can be understood as an internally reflecting reflection layer. Optically transparent in this context may mean in particular that the transparent base body is optically transparent at least both for the primary radiation and for the secondary radiation (conversion radiation). The main body may be made of glass (eg BK7 glass, quartz glass or sapphire glass) or of a plastic, for example.

The reflection layer may be a single-layer or multi-layer layer, for. A single-layer silver or aluminum layer or a multilayer silver and / or aluminum layer (eg MIRO or MIRO-SILVER) or a multilayer interference layer stack.

The lens (in particular as a combination of the transparent base body and the reflection layer) furthermore has at least one first focal point and at least one second focal point. By "at least one focal point" can be understood in particular a single focus or a plurality of (two or more) focal points. A focal point can be understood in particular to be an (at least almost) punctiform focal point. However, a focal point can be understood to mean a one-dimensionally extended combustion region, eg. B. a closed or not closed line. Such a line can also be understood as a continuous stringing together of possible punctiform focal points. A (firing) line can occur, for example, in a rotationally symmetrical lens, as an annular line of the possible foci resulting from rotation about the axis of rotation. In addition, a focal point can be understood to mean a two-dimensionally extended focal region, for. B. a focal spot. The fact that the lens has the at least one focal point may in particular mean that this at least one focal point can be realized by means of the lens, but does not necessarily have to be realized in interaction with a lighting device using the lens.

In addition, at least one first focal point lies at least partially on a surface area of the base body which is not occupied by the reflection layer. The lens furthermore has at least one phosphor element, which rests against the base body at a contact region (in particular, in a planar manner) which has at least one first focal point. The at least one focal point of the contact region therefore also lies in particular in an interface between the main body and the phosphor element. This results in the advantages that firstly waste heat of the phosphor element can be dissipated effectively via the then serving as a heat spreader or heat sink lens and secondly multiple, lossy light reflections at interfaces (in particular to air) can be avoided, as z. B. otherwise would occur in a color wheel.

A phosphor element may, in particular, be understood as meaning a body which has one or more phosphors. In particular, a phosphor can convert incident (excitation or primary) light of a particular wavelength or wavelength range (eg, blue light) into secondary light of typically longer wavelength (eg, red or green light), with waste heat in the form the so-called. Stokes heat is generated, which is derivable here through the body. The phosphor element may, for. B. a glued on the body body, z. Example, a ceramic phosphor plate or a plate with phosphor as filler of a transparent matrix material (eg., Silicone), be. The phosphor element may also be or have a metal phosphate.

For example, the phosphor element may be sintered onto the base body, blown up, applied by means of hydrogen bridge bonds, applied by means of an EPD process (for example using an optically transparent, conductive intermediate layer such as an ITO layer), sprayed on, printed (for example by knife coating), etc. become. The phosphor element may also be an integrated region in the main body, in which the phosphor is present as an admixture within this range, which can be carried out for example by means of a sol / gel process.

Secondary light emitted by a phosphor element passes through the base body, at least partially hits the reflection layer and, from there, as the contact region has at least one first focal point, it focuses on at least one second focal point. By targeted irradiation of primary light on the at least one phosphor element can therefore be coupled out at the second focal point (or in the vicinity thereof) at least secondary light.

It is therefore an embodiment that the reflection layer is reflective at least for the secondary light generated by the at least one phosphor element.

The reflection layer may basically be permeable to the primary light, z. B. in the case of a complete conversion of primary light into secondary light (full conversion), in which primary light is irradiated in particular over a large area on the lens. The reflection layer may alternatively be reflective for primary light, so that a primary light component to be coupled out can also be precisely adjusted.

The phosphor element can, for example, convert the incident primary light into secondary light at least substantially completely (eg with a degree of conversion of more than 95%) (full conversion). The secondary light may have multiple wavelengths in the presence of multiple phosphors. The phosphor element may only partially convert the incident primary light into secondary light (partial conversion). Unconverted primary light is typically re-radiated from the phosphor element, e.g. B. diffuse. If the reflection position for the primary light is permeable, the primary light, in particular unused, may emerge again from the lens. If the reflection position for the primary light is reflective, at the second focal point (or in the vicinity thereof) a mixture of primary light and secondary light may be coupled out.

It is still an embodiment that the surface of the base body has a coated with the reflection layer lateral surface with an ellipsoidal basic shape or is. This allows easy provision of the at least one first and second focal point. However, the shape is not limited thereto and may be, for. B. also be a spherical shape or a freeform.

It is also an embodiment that the surface of the base body has a planar surface ("base surface") extending in a main plane, in which base surface the focal points lie. Such a lens is particularly easy to produce. The base may also be considered as a flat sectional surface along a major plane of an ellipsoid, particularly ellipsoid of revolution.

It is also an embodiment that the surface of the base body is a partly in a main plane extending, truncated base surface, in which base at least one focal point on or near edges (called "cut edges", even if they are not produced by a cutting process will need). This allows greater flexibility in the direction of the light path in the main body. The truncated base surface can also be regarded as a flat sectional surface along a main plane of an ellipsoid, in particular ellipsoid of revolution, on which at least one, preferably two, further cuts are made in the remaining ellipsoid.

It is a further development that at least a first focal point and a second focal point, in particular all focal points, lie on or in the vicinity of edges or cutting edges.

It is also an embodiment that the surface of the base body has a beveled base surface, in which base surface complementary or associated first and second foci are on mutually bevelled areas has. This also allows a greater flexibility in the direction of the light path in the base body, and it can be a mounting of the phosphor element over a cutting edge can be avoided.

The bevelled areas can, for example, merge into one another at a ("cut") edge. Alternatively, the beveled base z. B. have a basic shape of a pointed or blunt cone sheath.

It is also an embodiment that the main body has a coupling-out region for coupling out light, which has at least one second focal point. This allows a small-area coupling-out area, which allows a high luminance of the coupled-out light. At the coupling-out area, a coupling-out optics can be set up, e.g. As a light guide, a lens, a concentrator, etc. The coupling optics can be integrated into the body.

It is yet an embodiment that the reflection layer has at least one window which allows light to be irradiated on at least one first focal point. As a result, primary light can be radiated onto the at least one phosphor element in a simple manner, in particular via the lateral surface of the main body. In particular, the reflection position can thus be configured in a simple manner (for example, not wavelength differentiation).

It is a particularly easy-to-implement training that the window is a clear window, so lets through light directly on the body. The main body is therefore in particular exposed or not coated in the region of the window.

It is a particularly effective development that the window has an anti-reflection coating.

It is also an embodiment that the lens in the region of the at least one window has a focusing area which differs locally from a basic shape of the surroundings of the window for focusing incident light onto a first focal point. This can, for. B. for adjusting a size and / or shape of the light spot at the focal point, a falling through the focusing on the phosphor element (primary) light beam can be flexibly shaped. In particular, the light bundle running in the main body can also be aligned in the course of this by an angle of incidence of the light incident from outside onto the focusing region. The focusing region may in particular be formed protruding outward or raised, in particular convex.

The lens is not limited to the provision of a focal point and / or a phosphor element and may, for example, have a plurality of first focal points and / or a plurality of phosphor elements.

Thus, it is a development that the lens has a plurality of phosphor elements, wherein the plurality of phosphor elements are distributed rotationally symmetrical about an axis of rotation of the lens, for. B. angularly offset about a longitudinal axis or axis of symmetry on the base. The phosphor elements can be shaped and / or distributed in particular ring sector shaped. As a result, a luminous flux can be increased.

It is still a further development that the lens has at least one phosphor element which has or may have a plurality of, in particular spatially separated, first focal points, that is, in particular also be irradiated by a plurality of, in particular spatially separated, (primary) light beams. Such a development may z. B. be particularly easy to produce. For example, the at least one phosphor element may be exactly one phosphor element, the z. B. ring sector shaped, in particular semicircular, is arranged, for. B. on the base.

Several incident on the body light rays may have (primary) light of the same and / or different wavelength or spectral composition.

It is yet an embodiment that the lens has a plurality of first focal points and a plurality of phosphor elements, wherein the phosphor elements rest on contact regions which have at least one respective first focal point. As a result, light can be coupled out at a plurality of outcoupling areas, which increases a luminous flux and / or via an irradiation of phosphor elements with different phosphors selective selection of the color or a color combination of the decoupled light allowed.

The material of the main body may have a homogeneous refractive index. Alternatively, the material of the base body may have a locally changing refractive index. In particular, the material of the main body may then be a gradient material, and the main body may in particular be a so-called GRIN body or gradient optics.

The object is also achieved by a lighting device having at least one lens as described above and at least one light source, in particular semiconductor light source for irradiating primary light on at least a first focal point through the main body of the lens, wherein the at least one first focal point arranged at least a phosphor element is adapted to at least partially (ie, partially converting or fully converting) convert the primary light into secondary light of a different wavelength.

The lighting device gives the same advantages as the lens and can be configured in an analogous manner. The at least one (primary or excitation) light beam passing through the main body is focused, in particular, on an associated first focal point (including possibly a focal spot) on which a phosphor element is located. This focal point may in particular be a selected or realized focal point from a group of possible foci constructively provided by the lens.

For example, a plurality of different (eg spatially separated and / or differently oriented) (primary) light beams can be radiated onto the main body of the lens and consequently directed through the main body to a plurality of spatially-spaced first focal points. These focal points can be assigned to different phosphor elements and / or at least in groups can be assigned to a common phosphor element. For example, a plurality of first focal points can be generated or realized on a common, extended phosphor element. Several different (primary) light beams can be radiated onto the base body, in particular through respective windows or windows that are at least in groups.

It is an embodiment that the lighting device has a plurality of, in particular matrix-shaped, lenses. Thus, an increased luminous flux can be generated. Alternatively or additionally, a simple way of generating each coupled light with different colors will be provided, for. B. by providing at least two lenses with phosphor elements with different phosphor. Also, a particularly simple possibility for irradiation of primary light of different spectral width or different wavelength is provided (which, however, can basically also be realized with a single lens).

In particular, it is an embodiment of a lighting device with a lens which has a base body with a coupling-out region which has at least one second focal point, that a coupling-out optical system is arranged on at least one coupling-out region. The at least one coupling-out optics may be spaced from the lens, in particular its base body. For a loss-free as possible light emission or light extraction from the lens, the at least one coupling-out optics on the base body or contacts this. For a particularly loss-free light extraction and stable and easy handling, the at least one coupling-out optics is integrated into the lens, in particular its base body. Such integration can z. B. can be achieved by a common mold for glass or plastic.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 shows a sectional side view of a first lighting device with a lens according to a first embodiment;

2 shows a sectional side view of a second lighting device with the lens according to a second embodiment;

3 shows a sectional side view of a third lighting device with a lens according to a third embodiment; and

4 shows a sectional side view of a main body of a lens according to a fourth embodiment.

1 shows a first lighting device 11 with a lens 12 according to a first embodiment. The Lens 12 has one as a solid body of a solid transparent material, for. As glass or plastic, trained body 13 on.

The main body 13 has two mentally different surfaces, namely a lateral surface 14 with an ellipsoidal basic shape and a flat base 15 , The base area 15 extends in a main plane H of the ellipsoidal basic shape of the lateral surface 14 , The main body 13 thus has a rotationally symmetric axis of symmetry A.

The lateral surface 14 is mostly, that is, except for a window 16 , with an internally reflecting reflection layer 17 occupied, which in the direction of the main body 13 is formed reflective. The base area 15 however, it is not reflective 17 occupied and thus exposed. In or on the floor area 15 are a first focus F1 and a second focus F2. The exact position of the first focus F1 and the second focus F2 on the base 15 is due both to the shape of the reflection position 17 as z. B. also the refraction property of the body 13 certainly.

On the ground 15 is also a phosphor element in the form of a phosphor plate 18 applied flat, in a contact area 19 which has the first focus F1. The phosphor plate 18 For example, it can be glued on. Alternatively, the phosphor element z. B. imprinted or sprayed on his.

On the ground 15 is also at a decoupling area 20a a decoupling optics 20 attached, at the location of the second focal point F2. The decoupling optics 20 serves for coupling and light conduction of existing at the second focal point F2 light. The decoupling optics 20 , z. As a light guide or an optical concentrator, like the base 15 contact, for. B. be pressed or glued thereto, or may be integral or integral with the body 13 be formed, z. B. an area of the body 13 form.

The lighting device 11 also has a primary light source in the form of a semiconductor light source 21 (For example, comprising at least one laser or light emitting diode), which is arranged and arranged, emitted from it or emitted (primary) light P from the outside through the window 16 into the main body 13 to radiate. The primary light can z. B. be blue light. For this purpose, the semiconductor light source 21 a, in particular collimating, optics O be downstream.

From the lenticular body 13 the primary light P is focused on the first focus F1. As the phosphor plate 18 gap-free on the base body 13 rests, it is largely lossless irradiated by the primary light P. The phosphor plate 18 converts the primary light P at least partially into at least one secondary light S of a larger wavelength, z. B. in yellow secondary light S.

From the phosphor plate 18 converted secondary light S and possibly unconverted primary light P is at least substantially non-directional directly into the body 13 blasted. The reflection position 17 is reflective here designed both for the secondary light S and for the primary light P reflective, so that of the phosphor lamina 18 radiated light, in particular mixed light P, S, is reflected to the second focal point F2 and there by means of the coupling-out optics 20 is decoupled. The coupled-out mixed light P, S can be in particular white mixed light. Especially in the case that the phosphor plate 18 also has a blue-red converting phosphor, the mixed light may be a warm white mixed light.

The main body 13 and / or the lens 12 may be shaped rotationally symmetrical about the symmetry axis A formed. The lighting device 11 Just like the one window 16 , only the one semiconductor light source 21 and only the one phosphor tile 18 exhibit.

Alternatively like the main body 13 and / or the lens 12 For example, by 180 ° or less rotationally symmetrical (ie continuously) to be formed about the axis of symmetry A. For example, the phosphor plate likes 18 as an extended by 180 ° or less, ring sector-shaped phosphor plate 18 be educated. The Lens 12 also likes a correspondingly rotationally symmetric extended window 16 or a plurality of rotationally symmetrical (ie spaced angularly arranged) arranged around the axis of symmetry A window 16 exhibit. As a result, a plurality of primary light beams can be generated at respective first focal points F1 and light S, P can be coupled out at a plurality of second focal points F2. This may increase a luminous flux, z. B. proportional to a number of realized first foci F1, in particular if several semiconductor light sources 21 be used.

In another alternative like the body 13 and / or the lens 12 be designed, for example, 180 ° or less rotationally symmetrical about the axis of symmetry A. The lighting device 11 then in particular a plurality of spaced around the axis of symmetry A phosphor lamina 18 which have the same phosphor or different phosphor (eg, blue-yellow converting phosphor in a phosphor plate 18 and yellow-red converting phosphor in another phosphor slide 18 ) having.

The lighting device 11 like several, in particular arranged in a matrix, lenses 12 and related elements, e.g. B. 20 . 21 , exhibit. The lenses 21 etc. possible in particular in a common plane (here, for example, in a plane perpendicular to the image plane and corresponding to the base surface 15 ) be arranged side by side. This allows an increased luminous flux.

2 shows a sectional view in side view of a second lighting device 31 with the lens 32 according to a second embodiment. The lighting device 31 shows a similar basic structure to the lighting device 11 , But while with the lighting device 11 the primary light P through a window disposed at least approximately above the first focal point F1 16 At least approximately perpendicular is irradiated, the primary light P in the lighting device 31 by a window arranged at least approximately above the second focal point F2 16 at least approximately horizontally irradiated.

3 shows a sectional side view of a third lighting device 41 with a lens 42 according to a third embodiment. The third lighting device 41 is similar to the lighting device 11 built, but now has a body 43 on, its base area 45 not flat, but tapered beveled. The in the base area 45 lying focal points F1, F2 are on, in this illustration, against each other inclined areas 45a respectively. 45b the base area 45 , As a result, a run of the phosphor plate 18 radiated light S, P are formed more flexible, in particular to the direction of the coupling-out optics 20 ,

In addition, the basic body 43 in the area of the window 46 a locally deviating from the ellipsoidal basic shape focusing area 47 for focusing the incident primary light P on the first focus F1. The focus area 47 is designed as a convex, lenticular elevation and here to increase the light output with an anti-reflection coating 48 coated.

4 shows a sectional view in side view of a main body 53 a lens 52 according to a fourth embodiment. The main body 53 furthermore has an ellipsoidal lateral surface 54 on. The base area 55 is beveled several times and has a lying in the main plane H subarea 55a on. The base area 55 is further shaped cut and has cut edges K1 and K2, to which the portion 55a in beveled sections 55b respectively. 55c passes. The subareas 55b and 55c have a different angle to the main plane H. The foci F1 and F2 and consequently the phosphor plate 18 and the coupling-out optics lie on the cutting edges K1 and K2.

Although the invention has been further illustrated and described in detail by the illustrated embodiments, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2011/127286 A1 [0002]
• US 2007/019408 A1 [0003]

Claims (12)

Lens ( 12 ; 32 ; 42 ; 52 ) with a transparent base body ( 13 ; 43 ; 53 ), where - a surface ( 14 . 15 ; 14 . 45 ; 54 . 55 ) of the basic body ( 13 ; 43 ; 53 ) at least partially with an internally reflecting reflection layer ( 17 ), - the lens ( 12 ; 32 ; 42 ; 52 ) has at least one first focal point (F1) and at least one second focal point (F2), - at least the first focal point (F1) at least partially on an unoccupied surface area of the basic body ( 15 ; 45 ; 55 ) and - at least one phosphor element ( 18 ) on the base body ( 13 ; 43 ; 53 ) at a contact area ( 19 ), which has at least one first focal point (F1). Lens ( 12 ; 32 ; 42 ; 52 ) according to claim 1, wherein the reflection layer ( 17 ) at least for the at least one phosphor element ( 18 ) generated secondary light (S) is reflective. Lens ( 12 ; 32 ) according to one of the preceding claims, wherein the surface of the base body ( 14 . 15 ) one with the reflection layer ( 17 ) occupied lateral surface ( 14 ) with an ellipsoidal basic shape and in a main plane (H) extending, flat base ( 15 ), in which area ( 15 ) the foci (F1, F2) lie, has. Lens ( 52 ) according to one of claims 1 or 2, wherein the surface of the main body ( 53 ) one with the reflection layer ( 17 ) occupied lateral surface ( 54 ) with an ellipsoidal basic shape and a partly in a main plane extending, truncated base surface ( 55 ), in which area ( 55 . 55a . 55b . 55c ) at least one focal point (F1, F2) lie on or in the vicinity of cut edges (K1, K2). Lens ( 42 ) according to one of claims 1 or 2, wherein the surface of the main body ( 43 ) one with the reflection layer ( 17 ) occupied lateral surface ( 14 ) with an ellipsoidal basic shape and a beveled base ( 45 ), in which area ( 45 ) complementary first and second foci (F1, F2) on mutually tapered areas ( 45a . 45b ). Lens ( 12 ; 32 ; 42 ; 52 ) according to one of the preceding claims, wherein the basic body ( 13 ; 43 ; 53 ) a decoupling area ( 20a ), which has at least one second focal point (F2). Lens ( 12 ; 32 ; 42 ; 52 ) according to one of the preceding claims, wherein the reflection layer ( 17 ) at least one window ( 16 ; 46 ), which allows a light irradiation on at least a first focal point (F1). Lens ( 42 ) according to claim 7, wherein the lens ( 42 ) in the region of the at least one window ( 46 ) one of a basic shape of the environment of the window ( 46 ) locally deviating focusing area ( 47 ) for focusing incident light (P) to a first focus (F1). Lens ( 12 ; 32 ; 42 ; 52 ) according to one of the preceding claims, wherein the lens ( 12 ; 32 ; 42 ; 52 ) a plurality of first focal points (F1) and a plurality of phosphor elements ( 18 ), wherein the phosphor elements ( 18 ) at contact areas ( 19 ), which have at least one respective first focal point (F1). Lighting device ( 11 ; 31 ; 41 ; 51 ), comprising - at least one lens ( 12 ; 32 ; 42 ; 52 ) according to one of the preceding claims and - at least one light source, in particular semiconductor light source ( 21 ), for the irradiation of primary light (P) on at least one first focal point (F1) by the main body ( 15 ; 45 ; 55 ) of the lens ( 12 ; 32 ; 42 ; 52 ), wherein the at least one first focal point (F1) arranged at least one phosphor element ( 18 ) is adapted to at least partially convert the primary light (P) into secondary light (S) of a different wavelength. Lighting device ( 11 ; 31 ; 41 ; 51 ) according to claim 10, wherein the lighting device ( 11 ; 31 ; 41 ; 51 ), in particular arranged in a matrix, lenses ( 12 ; 32 ; 42 ; 52 ) having. Lighting device ( 11 ; 31 ; 41 ; 51 ) according to one of claims 10 or 11 with at least one lens ( 12 ; 32 ; 42 ; 52 ) according to claim 6, wherein at least one extraction area ( 20a ) a decoupling optics ( 20 ) is arranged.

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